In order to measure neuronal activation related rCBF changes quantitatively, we have developed a Flow-sensitive Alternating Inversion Recovery (FAIR) technique, in which perfusion-based functional images can be generated by subtracting two IR images, one with a non-slice-selective IR pulse and another with a slice-selective IR pulse. The method was employed in functional imaging studies of the motor cortex. Activation of the contralateral motor cortex was detected during finger movements in FAIR images. The signal change (~SFAIR) of contralateral motor cortical area in four subjects detected by the FAIR technique was 49 +/- 16% SD, which is in good agreement with PET studies of blood flow.